This invention relates to an image processing apparatus for processing image video signals from an image signal source, such as a video camera, and more particularly to an image processing apparatus and method, which have made it possible to simultaneously access an image memory for processed input data and a process memory for data by a plurality of access circuits.
A known conventional image processing apparatus for processing video signals is an apparatus which has an image memory for storing digitized input image signals and a process memory for storing processed video signals, and which is arranged to access those memories with a plurality of access circuits to process or output the video signals.
In the above-mentioned type of image processing apparatus, between the access circuits there are provided access control circuits for monitoring the operating conditions and controlling the operation of the access circuits.
The access control circuits control the access circuits so that the access circuits operate mutually independently and that the same memory is not accessed by a plurality of access circuits. More specifically, while a first access circuit is in the process of accessing the memory, if a second access circuit is going to access the memory, the second access circuit sends an access request signal to the first access circuit and waits. The second access circuit does not become accessible until an access permission signal is sent from the first access circuit.
The image processing apparatus such as this has a problem that processing time is long because a next access circuit starts its access operation when some other access circuit has finished an access operation.
If this problem is solved by using parallel processing, another problem arises that it is necessary to provide many access buses and circuits for access switchover and the circuit configuration becomes complicated.
If video signals are to be processed which are sent from a plurality of video cameras, a possible method is to provide each video camera with a corresponding memory and perform parallel processing of video signals from different video cameras. In this case, the process proceeds relatively quickly, but a problem with this method is that the image processing apparatus is complicated, large in scale, and expensive. On the other hand, another possible method is to use a common memory for different video cameras and thereby prevent the image processing apparatus from becoming complicated, larger in scale, and high in cost. However, a problem with this method is that video signals from different video cameras cannot be processed simultaneously and a long time is required for the process.